Meteorological Instrumentation

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Meteorological Instrumentation
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Why is this important?
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So, why is this important?

• No substitute for direct observation
• Provides the best estimate of physical quantities
• Provides the groundtruth for remotely sensed
  quantities
• Provides the initial conditions for modeling

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Know your data

• If you use numerical data, know the meta data
  data about the data
• How was the data recorded?
• Automated
• Direct
• What type of instrument was used
• What are the errors associated with that
  instrument
• In a time series of observations, what is the
  variability in
• Timing
• Location
• sensor

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The Measurement Process

• The quantitative determination of a physical
  magnitude by comparison with a fixed magnitude
  adopted as a standard or by means of a calibrated
  instrument
• We have to know what were measuring
• Our measuring device must be calibrated
• There must be a scale

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Measuring Devices

• In some cases the comparison is direct
• Measuring stick
• A balance
• Most often the comparison is made indirectly
  using a sensor which exhibits a predictable,
  quantifiable change in response to changes in the
  physical quantity being measured
• Mercuryin-glass thermometer

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Characteristics of measuring devices

• Accuracy
• How close is the measurement to the true value
• Precision
• If repeated measurents are made of the same
  quantity, what is the variability among the
  measurements
• Sensitivity
• How much change in the measuring device is
  produced by a given change in the measured
  quantity

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• Resolution
• What is the smallest change in the measured
  quantity that is detectable by the measuring
  device
• Hysteresis
• How does the measurement differ if the measured
  quantity is increasing toward a value versus
  decreasing toward a value
• Responsiveness
• How long does it the measuring device to obtain a
  new value after a change in the value of the
  measured quantity

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Additional Problems

• Site selection
• Temporal sampling
• Spatial sampling

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